Is backbiting shirk?

Q: Does backbiting mean its shirk and after judgement we cannot go to paradise even after Nabi (sallallahu alaihi wasallam)'s intercession?

If I backbited and do not go to the person because of feeling shy, how can I tell this person? Can we do tauba so that Allah knows that we tried our best not to backbite? Can this be forgiven?.

Making qadha if haidh started during a salaah time

Q:

1. My menstruation cycle is regular in the sense that I have 14 clean days, 1 day istihaza and 10 days haiz. It's the same every time. So it starts at 4.43pm. I am usually always alert about performing my asr salaah before the time of haiz starts. Unfortunately today I was unwell earlier and had to sleep and over slept and only awoke after the time of haiz began. Will this asr Salaah be considered as qaza?

2. As a saahib tartib if I make ghusl and I have only enough time to perform the fard salaah and not the qazaa. When do I read the qazaa?

Woman covering the feet in salaah

Q: Is not covering the feet below the ankles for woman against sunnah? I have severe waswasa and I found out that except for Hanafi's, others consider the feet as awrah. Are my prayers invalid as I didn't cover it after knowing about the ruling. Why do Hanafi's not consider the feet as awrah. I feel scared that my namaz isn't valid. What should I do?